Resistor



Aug. 27, 1963 c. F. MITTELSTADT RESISTOR Filed July 5, 1961 lNvEN-roR I4 Clarence F. Mitelstad This application relates to a resistor for introducing resistance into an electrical circuit. The resistor is constructed s o as to make unprecedentedprovision for the circulation therethrough of air to prevent overheating ,y United States Patent O of the resistor. Also the resistor is made upof elements which when assembled provide for 'exceptionally good electrical conductivity therebetween. The resistor is of comparativelyk simple construction, economical to manufacture, compact and of light weight. I accomplish improved results While at the same time effecting-a reduction in cost.

I provide a resistor comprising supporting means including spaced'apart members of non-conducting material, such members having openings therein, an elon-l gated resistance element having a body ofy coil form,

the end` portions of the resistance element entering the openings in the spaced apart members, and means mounting the resistance element to the supporting means, the

supportingv means being open transversely of the resistance element to permit air circulation transversely through theycoil. The eud portionsof the resistance element and the means mounting the resistanceelement to the supporting means preferably have openings therethrough extending generally inthe direction of the length' of the resistance element to permit additional air circulation through such openings. The end portions of theresistance element may comprise externally threaded'nipples having axial openings therethrough, .and the means mounting the yresistance element to the supporting means may comprise nuts threaded onto the externally threaded nipples.

I preferably provide a plurality of elongated resistance elements each having a body of coil form with the end applied in 'generally' coaxial relation to the coil by weld means and means including an externally threaded nipple may be threaded into the rinternally threadedend mem-.

ber for mounting the resistance element in a supporting structure. f

More specifically my resistance element may comprise a coil having applied to an end thereof an end structure comprising means for mounting the resistance element ink a supporting structure, the end structure having therethrough a tapered opening adapted to act -as a socket to receive a plug in electroconductive relation thereto and when no plug is in the socket to 'permit circulation of air through the end structure. The end structure may comprise a central projection externally threaded toV re-` ceive a nut to fasten the resistance element to a plate or 'connector ithrough which the central projection is adapted to pass and. at least one boss or protuberance beside? the central 'projection adapted to enter acavity in the plate or connector to establishjan electrical connection between 'the resistance element and lthe plate. The pro- "ice muberance and the cavity 'are preferably tapered to afford tight rictional engagement therebetween enhancing the n electrical conductivity of the connection between the resistance element and the plate. I lind it desirable to employ diametrically opposed protuberances on opposite sides of the projecting portion of the end structure of the resistor and correspondingly positioned cavities in the connector receiving the protuberances. However, the protuberances may be formed on the connector and the cavities may be formed in .the end structure.

Other details, objects and advantages of the invention will become apparent as `the following description of a present preferred embodiment thereof proceeds.

In the 4accompanying drawings l have shown a present preferred embodiment of the invention in which FIGURE 1 is a plan view. of one complete resistor and a portion of a second resistor showing means for electrically connecting the resistors together;

FIGURE 2 is a side-view of the complete resistor shown in FIGURE l;

FIGURE 3 isa cross-sectional view taken on the line III-III of FIGURE 2,

FIGURE 4 is an isometric view of a plate or connector with a por-tion cut away;

FIGURE 5 is an isometric view of the resistor end structure; and

FIGURE 6 is a cross-sectional isometric view of the resistorgend` structure to show the tapered socket therein.

Referring now more particularly to the drawings, my resistor comprises a case designated generally by the reference numeral 2 which may be of any suitable material, such as metal or plastic, with opposed ends 3 and four sides 4 provided"with openings `S for the circulation'of air through the resistor. Mounted in the case 2 are spaced apart supporting means 6 of non-conducting material such as Transite, such members being shown as being positioned respeotively adjacent the ends 3 of the case. Another member 7 of similar material is shown intermediate the members 6r. The member 7 may be omitted if desired, particularly if the resistor is short in the direction between the ends 3; if the resistor is relatively long in the direction between lthe ends 3 the member 7 is preferably utilized to assist in insuring maintenance -of proper positioning in the case of the resistance elements now to'be described.

The resistor mounted in the case 2 comprises two resistance elements each designated generally by reference numeralS. The resistance elements 8 may be constructed in' generally similar manner so description of kone will suflice for both. Each resistance element 8 has a body in the form of a coil 9 (although the coils are shown as being specically dilierent as to size of wire and pitch) and end structures designated generally by reference numeral 1l)y at its respective ends. Each coil is wound from high resistance stainless steel Iwire which is corrosion resistant and laterally open (i.e., the convolutions of the coil are spaced apart) to permit cooling air entering the case through .the openings 5 lto pass between the convolutions of the coil to cool the coil. Such shape of the coil also sets up a turbulence of the cooling air which enhances the cooling effect.

Welded to each end of the coil 9 is an end structure 10 as shown in FIGURES 5 land 6. 'Each end structure y10 comprises anv internally threaded end member 11 which is welded to the coil in @generally coaxial rela-tion thereto by weld metal 12. Threaded int-o each end member 11 is an externally threaded nipple 13 having a tapered opening 14 therethrough adapted to act as a socket to receive fa tapered-plug in electroeoonductive relation thereto as will presently be described and when no plug is in the socket to permit circulation of air through the end structure. The nipple 13y is preferably welded to the end member 11 by weld metal 15. The word weld is used .he-reinas a word of broad definition and not of limitation and includes a connection for-med by processes analogous to welding such as brazing soldering, etc.

By the same'token theter-m wel-d metalf oom'- prehends brazing metal, soldering metal, etc. The end I member 11 with the nipple '13' permanently attached i thereto las above described jointly form theend structure of the resistance element with the nipple constituting nector 19 as shown in FIGURE 4 is applied to each end. of the resistor. Each connector 19 has two openings 20 for receiving the projecting portions 13 of the end structures of the two resistance elements, tapered cavities 21 for receiving 4the'protuberances'l and a central hole 26 for receiving a self-tapping screw to tasten the connector lclaim: l. A resistor comprising supporting means'including spaced apart members of non-conducting material, said members havin-g openings therein,- lan elongated resistance clement having a body of coil zform, the end portions of y' the resistance element` entering said openings, and means mounting theresistance element to the supporting means,v f

the end portionsof the resistance element and the means mounting the resi-stance element to the vsupporting means having openings extendingcompletely therethroughk generally in the direction of the length of the resistance ele? ment 'to permit air circulation therethrough. L

,2. A resistor comprising supporting means including spaced apart members of non-,conducting material,` said members having openings therein, yan elongated resistance` clement having a body of coil form, the endportions of l the resistance element entering said openings, and means yto the adjacent supporting member 6i. Each cavity 21 g is tapered from relatively greattransverseldimension toward the inside of the resistorto relatively small transverse dimension toward the outside off the resistor. Similarly each protuberan'ce 16 is ltapered from relatively ygreat transverse dimension toward the inside of the resistor to relatively small transverse dimension toward the ,y outside of the resistor provid-ingv `for easyv entry Yof the vmounting the resistance element to the supporting means, `1

the supporting means being open transversely ofthe re sistance,l element to permit air circulation transversely through the coil, they end port-ions of -thejresistance ele-V ment and the means, mounting the-resistance elementto lthe supporting means having openings extending comn pletely therethrough generally .in the direction oQthe lcngthot the resistance element to permit Vadditional-'air circulation through the last mentioned openings.

protuberances 16 into the cavities 21 and for insuring. a

tight frictional connection between each protuberance and the wallof the :corresponding cavity and optimumv surface contact between the resistance' element and the connector whereby to enhance the electrical conductivityv i ofthe connection between the resistance element and thev connector and hence also the electrical conductivity be-v connected ybyfia connector. Nuts 23 are threaded onto the ynipples 13 and tightened against the connectors 19` and serve the dual function of mounting kthe resistance element-s in the'case andrtightly pressing the rtapered proj tuberances 16 into the tapered cavities 21.-- When the nuts 23 are tightened the connectors 19 are pressed against the outer faces of the supporting members 6, the

j resiliency of the springs 9 insuringv a'rm and tight connection at both ends of the case.

A conduct-or 724 may be v provided with Vtapered plugs `3. A resistor comprising supporting means including n spaced apart members `of nonJconductingkmaterial, saidz members having openings therein, ian'elongated resistance v element havingravbody of coil form, they end poitions of the resistance element yentering said openings, and means mounting the resistance element to the supporting means, v theend portions of the resistance element comprising externally threaded nippleshaving axial openings'extend`- Y ing completely therethrough and the means mounting the resistance clement'to the supportingmeans comprising y nuts threaded onto the externally threaded nipples. tween adjacent resistance `elements-whichare electrically 4.1'A 'resistanceelennent comprising a coil having anV internally threaded end member applied liny generally co-M axial relation to the coil, weld means for fasteningl said member .to the coil and means including `an externallyA threaded nipple threaded into the internally threaded end member formounting theresistancerele'ment in fa ksupporting structure.

25 yat its ends which may (be introducedy into the tapered 1 sockets 14 of resistance velements in adjacent resistors so as to electrically 'connect the resistors together. The

Y taper ofthe plugs 25 and the taper of the sockets 14 may` `5., A resistance `element comprising -a `'coil having ap-` plied to anend thereofan end structure comprising means for mountingthe resistance element in a supporting struc-A ture,.the endstructurehaving a tapered opening extendf ing completely therethrough adapted to act as a* socket v` to receive a plug in electroconductive relation thereto and when no plug is in the socket torpermit circulation of air through the end-structure.

be substantially the same so that the plugs are maintained in the sockets by frictional engagement over a large surface Iarea. This insures retention of the plugs ;k in the `sockets and ian optimum electrical connection between adjacent resistors.V i i The end members 11 land *the connectors 19y are desirably cast out' of 'high strengthlow resistance bronze which can be welded to stainless steel at about' 1500f F. which is the annealing tempera-tureof the wire used for the `coils.

manner as to maintain fusionof the weld metal atthe annealing temperature of the coil wire. The supporting members `6 and 7` maybe made of Transito treated to' resist temperatures of 230W F., heat load and shock and provide insulation 'for 10,00()tv `volts between coils and y be otherwise variously embodied within the Iscope of the f following claiInS` l' The end members are welded to the coils by j deposit welding employing ra welding rod and in such `6. vA resistance element comprising a coil having ap- .v a plied to .an end thereof au end structure comprising a central projectionaenternally threaded 4to receive' a nutl to fasten the resistance element to a plate through which the central projection is adapted to pass and an outwardly projectingu protuberance )adapted to enter a cavity.y in the plate to assist in relatively positioning the en'dfstructure tween the resistance'element and the plate. l

7. A resistor comprising a resistance element having an end structure comprising a-projecting portion, a plate and the plate and enhancing the.electrica1'connection behaving an opening through which the projecting portion of the endstructu-re of thev resistance element extends,

means 'cooperating with the part of the 'projecting portion of the end structure which extends through the openingl in y the plate and with the plate to tasten the resistance ele ment and the plate together, one of the endstructurewand Y V the plate having protuberance means and theother thereof having-cavity means .receiving the protuberance means to assist in, relatively positioning the Tend istructureand the plate and enhancing the'electrical connection 'between the resistance element and the plate.

A resistor comprising va resistance element having' an end structure 'comprising a projecting pention, a plate having an opening through which the projecting portion of lthe end structure off the resistance element extends, means Icooperating with the part of the projecting portion .of the end structure which extends Ihnen-gh the opening in fthe plate and with the plate to fasten fthe resistance element and the plate together, one lof the end structure and the plate thawing tapered protnbenance means and the other thereof 'having tapered 'cavity means receiving the protuberance means to assist in relatively positioning Ilthe end `structure and -the plate and enhancing the electrical connection between the resistance element and the plate.

9. A resistor comprising la resistance element having an end structure comprising la projecting portion, a plate having an opening tihnongh which the projecting portion of the end structure of the resistance element extends, means cooperating with fthe pant of the projecting portion of the end structure which extends through the opening in the plate and with .the plate to lfasten the resistance element .and the plate together, one of the end structure land the plate having pronuberfance means land. the other thereo having cavity means receiving the pnotnberance means to assist in relatively positioning the end structure and the plate land enhancing Athe electrical connection between the resistance element and the plate, the end structure having a tapered opening extending completely there through adapted to 'act as a #socket to receive a plug in electroconductive relation thereto and when no plug is in the socket to permit circulation of anthrough the end structure.

References Cited in the le of this patent UNITED STATES PATENTS 963,396 Robinson July 5, 19-10 2,373,156 Wilhelm c Apr. 10, 1945 'Fot Mar. 30, 1948 

1. RESISTOR COMPRISING SUPPORTING MEANS INCLUDING SPACED APART MEMBERS OF NONE-CONDUCTING MATERIAL, SAID MEMBERS HAVING OPENINGS THEREIN, AN ELONGATED RESISTANCE ELEMENT HAVING A BODY OF COIL FORM, THE END PORTIONS OF THE RESISTANCE ELEMENT ENTERING SAID OPENINGS, AND MEANS MOUNTING THE RESISTANCE ELEMENT TO THE SUPPORTING MEANS, THE END PORTIONS OF THE RESISTANCE ELEMENT AND THE MEANS MOUNTING THE RESISTANCE ELEMENT TO THE SUPPORTING MEANS HAVING OPENINGS EXTENDING COMPLETELY THERETHROUGH GENERALLY IN THE DIRECTION OF THE LENGTH OF THE RESISTANCE ELEMENT TO PERMIT AIR CIRCULATION THERETHROUGH. 